Summary:
There are cases where native modules will try to reference other native modules during startup, which can causes a deadlock on `RCTModuleData::_instanceLock`.
My system was in a state where the deadlock would repro 100% so I could actually debug it a bit, but really this whole system is very fragile and needs to die in a fire.
I tried a recursive lock and it was not sufficient - there are definitely issues with multiple threads invoking at the same time and then calling `RCTUnsafeExecuteOnMainQueueSync`...
Reviewed By: fkgozali
Differential Revision: D14863583
fbshipit-source-id: 8c0d062353595a4ed3871aa9135950bc57983907
Spencer Ahrens
b1f1c5375c